FIG. 1 shows an exemplary Wide Field of View (WFOV) lens system. The lens system shown includes a hemispherical field of view mapped to a planar image sensor for example as shown in FIG. 2.
This mapping can tend to result in variations in acquired image distortion and resolution across the field of view. It is desired to correct for this distortion so that, for example, features such as faces or other objects, especially those located towards the periphery of the field of view, do not appear distorted when displayed.
Separately, WFOV systems can tend to especially introduce heavy and in some cases non-uniform distortion patterns across the field of view so that acquired images (or indeed different colour planes of an acquired image) do not uniformly conform to the ideal mapping shown in FIG. 2. Thus, it is desired to also correct for this type of distortion, as well other types of optical distortion that can tend to occur within digital images.
In a high definition image acquisition device, sometimes enormous amounts of information are received and transmitted across the system bus at high frame acquisition speeds. This places pressure on many processing modules that may be connected to the system bus to ensure their demands on the system bus are within an allocated budget and so do not interfere with other processing. The processing modules themselves may be implemented in certain embodiments with a reduced or minimal hardware footprint so as to minimize device production costs.
U.S. Pat. No. 5,508,734, which is incorporated by reference, discloses a WFOV lens assembly designed to optimize the peripheral regions of the field of view to provide improved resolution matching between the peripheral region relative to a central region, the peripheral region tending to have a lower resolution than the central region.
US 2010/0111440, which is incorporated by reference, by Chai, discloses a distortion correction module which partitions coordinate points in a selected output image into tiles. The output image is an undistorted rendition of a subset of the lens-distorted image. Coordinate points on a border of the tiles in the output image are selected. For each tile, coordinate points in the lens-distorted image corresponding to each selected coordinate point in the output image are calculated. In addition, for each tile, a bounding box on the lens-distorted image is selected. The bounding box includes the calculated coordinates in the lens-distorted image. The bounding boxes are expanded so that they encompass all coordinate points in the lens-distorted image that map to all coordinate points in their respective corresponding tiles. Output pixel values are generated for each tile from pixel values in their corresponding expanded bounding boxes.